1. Field of the Invention
This invention relates to a process for coloring fibrous structures, and, more specifically, to a process for coloring fibrous structures which provides colored fibrous structures with brilliant colors and superior fastness characteristics and also little contamination due to unfixed coloring agents in the uncolored portions, i.e., white background, and the colored portions.
2. Description of the Prior Art
When various fibers are colored by dyeing or printing, a small amount of the unexhausted or unfixed coloring agent is always present on the fibers. Such an unexhausted or unfixed coloring agent contaminates the colored portions or the uncolored portions of the fibers during soaping in the coloring process or during washing in use, and also dulls the color of the colored portions or reduces the brilliancy of the color and reduces the fastness of the colored fibers. Not only when a single dye is used for a single kind of fibers, but also when a plurality of dyes are used in order to obtain the desired color densities, the contamination of the fibers by the unfixed or unexhausted dyes is quite marked.
Nowadays, a great variety of fibers are used including natural fibers such as flax, cotton, silk or wool, semi-synthetic fibers such as viscose, acetate or triacetate fibers, and synthetic fibers such as polyvinyl alcohol, polyamide, polyester, polyacrylonitrile, or polypropylene fibers. These fibers differ from each other in chemical composition and properties, and a variety of dyes are used for coloring these fibers as shown in Table 1.
TABLE 1 __________________________________________________________________________ Kinds of Fibers Kinds of Dyes Metal- Copper Naphthol contain- Dir- treated and Its Soluble Re- Pig- Basic Acid Chrome ing ect Direct Vat Derivatives Vat Disperse active ment __________________________________________________________________________ Natural Fibers Cotton (0) 0 0 0 0 0 0 0 0 Flax 0 0 0 0 0 0 0 0 Wool (0) 0 0 0 0 0 0 (0) Silk (0) 0 0 0 0 (0) (0) 0 (0) Semi-Synthetic Fibers Viscose (0) 0 0 0 0 0 0 0 0 Acetate (0) 0 0 (0) 0 (0) Synthetic Fibers Polyamide 0 0 0 (0) 0 0 (0) Polyvinyl Alcohol 0 0 0 0 0 (0) Polyester (0) 0 0 (0) Modacrylic 0 0 (0) (0) 0 (0) (0) Acrylic 0 (0) (0) 0 (0) Vinylidene Chloride 0 (0) Vinyl Chloride 0 0 0 0 (0) Polyurea 0 0 0 0 (0) Polypropylene 0 0 0 (0) Triacetate 0 0 (0) 0 (0) Polyurethane 0 0 0 0 (0) (0) __________________________________________________________________________ O : Usually used for dyeing and printing (O) : Usable but partly limited
In order to utilize the physical and chemical properties of these fibers, these fibers are frequently used in a mix-spun or mix and interwoven or interknitted state. Thus, a mixture of various dyes appropriate to the constituent fibers is used to color such a fibrous structure, and therefore, in almost all cases, some dyes have no dyeability for certain kinds of fibers and contamination caused by such dyes is great. In an attempt to prevent such contamination, the previous practice has been to wash the dyeings repeatedly using various detergents, or perform the repeated washing after dyeing the fibers in a multiple of baths. In spite of these efforts, entirely satisfactory results have never been obtained.
In view of this, we have made extensive investigation in order to remove these defects, and finally have arrived at this invention. It is therefore an object of this invention to provide a commercially advantageous process for coloring fibrous structures whereby colored fibers free from contamination by unfixed dyes and having a brilliant color tones and superior fastness characteristics are obtained using simplified process steps.